Models of Radioiodine Transport to Populations Within the Continental U.S.

Abstract

A methodology is being developed to estimate the exposure of Americans to 131I originating from atmospheric nuclear weapons tests carried out at the Nevada Test Site (NTS) during the 1950s and early 1960s. Since very few direct environmental measurements of 131I were made at that time, the assessment must rely on estimates of 131I deposition based on meterological modeling and on measurements of total beta activity from the radioactive fallout deposited on gummed-film collectors that were located across the country. The most important source of human exposure from fallout 131I was due to the ingestion of cows' milk. The overall methodology used to assess the 131I concentration in milk and the 131I intake by people on a county basis for the most significant atmospheric tests is presented and discussed. Certain aspects of the methodology are discussed in a more detailed manner in companion papers also presented in this issue. This work is carried out within the framework of a task group established by the National Cancer Institute.

The Assessment of Radiation Exposures in Native American Communities from Nuclear Weapons Testing in Nevada

“…(3,10)4 There is substantial uncertainty in these estimates as well as considerable interindividual variability in the doses received by individuals residing in the same location at the same times. 5 However, quantitative estimates of the uncertainty and variability are not routinely provided in the ORERP materials.…”

“…The models developed were used as templates for other dose reconstructions, such as the Hanford Environmental Dose Reconstruction Project, and provided experience in collecting and evaluating a wide variety of historical data. (2,5,6) Because it was early in the learning process there were also difficulties and deficiencies in the effort. The computational effort was very complex and is thus difficult to adapt to answering new questions.…”

“…The next highest internal doses were to the lower digestive tract, which reflects the passage of a variety of insoluble radionuclides 5. The importance of distinguishing uncertainty from variability is discussed at length in the National Academy report Science and Judgment in Risk Assessment.…”

New information on nuclear tests

“…The exposure of the American population to 131 I from the NTS atmospheric tests has also been considered by Bouville et al . [13]. This assessment concerned intake through ingestion and was undertaken on a county‐by‐county, and test‐by‐test, basis.…”

Naturally occurring 137Cs, 90Sr and 226Ra radionuclides in raw milk in the Sibiu province of Romania

“…Under the threat of environmental contamination with radioactivity, milk is an important source of human exposure because, unlike most foodstuffs, it is ‘harvested’ daily and may be consumed well within the half‐life of even short‐lived species of isotopes (Watson 1986; Bouville et al. 1990).…”